Noradrenaline release Flashcards

1
Q

What is the autonomic nervous system a part of?

A

The peripheral nervous system

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2
Q

What does the autonomic nervous system do?

A

Conveys all outputs from the CNS to the rest of the body except the motor innervation of skeletal muscle

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3
Q

What are the three divisions of the autonomic nervous system?

A

Sympathetic
Parasympathetic
Enteric

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4
Q

What does the autonomic nervous system regulate?

A
Smooth muscle tone
All exocrine secretions
Some endocrine secretions
Heart rate and force
Certain metabolic processes
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5
Q

What are the neurotransmitters of the parasympathetic nervous system?

A

Ach

Ach

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6
Q

What are the neurotransmitters of the sympathetic nervous system?

A

Ach

NAd

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7
Q

What is the first step of noradrenaline and adrenaline synthesis?

A

Tyrosine is converted to dihydroyphenylalanine

By tyrosine hydroxylase

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8
Q

What is the second step of noradrenaline/adrenaline synthesis?

A

Dihydroxyphenylalanine is converted to dopamine

By dopamine decarboxylase

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9
Q

What is the third stage of noradrenaline/adrenaline synthesis?

A

Dopamine is converted to noradrenaline

By dopamine beta hydroxylase

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10
Q

What is the fourth step of noradrenaline/adrenaline synthesis?

A

Noradrenaline is converted to adrenaline

By phenylethanolamine n-methyl transferase

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11
Q

Describe tyrosine hydroxylase

A

In the cytoplasm of catecholamine containing cells
Rate-limiting step
Feedback inhibition by NAd
Inhibited by alpha methyltyrosine

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12
Q

Describe dopamine decarboxylase

A

More widespread distribution
In cytoplasm
Inhibited by carbidopa

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13
Q

Describe dopamine beta hydroxylase

A

In catecholamine containing cells
In synaptic vesicles
Inhibited by nepicastat and etamicastat

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14
Q

Where is phenylethanolamine n methyl transferase found?

A

In A cells of adrenal medulla

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15
Q

What is alpha methyl tyrosine?

A

Inhibits tyrosine hydroxylase

Used in phaeochromocytoma

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16
Q

What is carbidopa?

A

Inhibits dopamine decarboxylase
Works in the periphery not CNS
Used in Parkinson’s

17
Q

What is methyldopa?

A

Taken up by sympathetic neurones
Converted to alpha methylnoradrenaline
Displaces noradrenaline from vesicles
Used for hypertension in pregnancy

18
Q

What is 6-OH dopamine?

A

Neurotoxin

Experimental use only

19
Q

What is nepicastat?

A

Dopamine beta hydroxyls inhibitor

Used in cocaine dependence

20
Q

What is etamicastat?

A

Dopamine beta hydroxyls inhibitor

Treating hypertension

21
Q

Where are noradrenaline and adrenaline stored?

A

Adrenal glands

In chromaffin glands

22
Q

What is reserpine?

A

Inhibits the vesicular amine transporter
Vesicular stores of catecholamine decrease
Previously used to treat hypertension

23
Q

What triggers exocytosis from sympathetic nerves?

A

Ca2+ influx

24
Q

What regulates the release of noradrenaline?

A

Sympathetic nerve terminals contain receptors for many mediators
Either facilitate or inhibit reduce of noradrenaline

25
What is autoinhibition?
Noradrenaline released from sympathetic varicosities acts on presynaptic receptors to inhibit its own release
26
Name some drugs that inhibit noradrenaline release
Acetylcholine Adenosine Opiods Angiotensin
27
What are the side effects of morphine?
Constipation | Pupillary dilation
28
What are the two stages of termination of adrenaline and noradrenaline action?
Uptake | Degradation
29
How are catecholamines taken up?
Neuronal | Non-neuronal
30
How does neuronal uptake work?
Noradrenaline transporter | Co transports Na+ Cl- and catecholamine
31
What inhibits neuronal uptake?
Cocaine Tricylic antidepressants Phenoxybenzamine
32
How does non-neuronal uptake work?
Not particularly selective for noradrenaline
33
What inhibits non-neuronal uptake?
Normetanephrine Steroid hormones Phenoxybenzamine
34
How are catecholamines degraded?
``` By intracellular enzymes Monoamine oxidase Catechol-O-methyl transferase Aldehyde dehydrogenase Aldehyde reductase ```
35
What are noradrenergic neuron blocking drugs?
Inhibit noradrenaline release | e.g. guanethidine, bretylium